Can I sharpen a file?

[Leigh Betsch]

I heard someplace that you can soak worn files in acid to sharpen them. I like to keep my old tools (like my old friends ya know), rather than replace them. Anyone have experience in this? Can I use muriatic acid or phosphoric acid?, I have some of each. A quick search says battery acid or pickling vinegar, I like to keep my battery acid inside my batteries and it seems pickling vineger would be a little weak.

[David Weaver]

Phosphoric acid will add a little to them, like any other acid, but they are going to be in a state of usable semi-dullness in my experience.

A trip to boggs tool will do a whole lot more for them.

I still use phosphoric where the state of semi-dullness is OK.

[Chris Fournier]

I have used muriatic acid to do this with qualified success. This process literally eats the metal of the file and it eats it back to a sharper edge at the tooth. For this reason the acid bath will revive a tired file very nicely but it will do no good for a file that is truely worn and kaput. The results are terrific but you should neutralize the acid left on the file in a soda bath after the file has been sharpened.

HERE IS A WARNING! The fumes from the acid will cause other metals in the vicinity to rust! This means DO NOT do this anywhere near your shop! I renewed some files last spring; I merely slipped them into the 1 gallon container to immerse them having wrapped wire around the tangs to retrieve them. The opening from the container was about 1 3/8" in diameter. I placed the jug on the driveway infront of my open shop overhead door and worked away merrily. Well I was merry until I looked at my LN handsaws on the wall and thought that the plates were not as shiney as they should be. Then scanning around the shop I saw a rust bloom on everything that I owned that was cast iron or steel. Nice. I scrubbed everything I owned to get the rust off.

Sharpen your files in the middle of a field, on a day with no wind with your shop doors and windows closed tight! Sure enough a light breeze was blowing the acid fumes into my shop - Doh!

[Leigh Betsch]

IHERE IS A WARNING! The fumes from the acid will cause other metals in the vicinity to rust!

Yikes! I'll set it out in the middle of my yard, long way from my shop. How long does the acid dip take, 15 min or 6 hrs?

[Jessica Pierce-LaRose]

If you can find a really really tiny diamond file, and have hours to waste, you could try to sharpen it the same way as a float... :P

[Chris Fournier]

Depends on the file Leigh but 45 minutes to an hour was all mine took. Glad that my tale of woe registered with you!

[Johnny Kleso]

PROS sand blast them from the back side at a low angle..

[Chris Fournier]

PROS sand blast them from the back side at a low angle..

Never heard of that. It would only remove material from one face of the cutting edge and that would require twice the material removal.

This is not to say that some folks do this.

[Leigh Betsch]

I soaked about a dozen of my files in muratic acid, forgot them for about three hours. They came out great!, definaltly sharper than they were. Thanks for the info.

[Chris Fournier]

It's such a rewarding technique when you don't foul up all of your other equipemt Leigh! Good to hear of your success.

[Johnny Kleso]

Never heard of that. It would only remove material from one face of the cutting edge and that would require twice the material removal.

This is not to say that some folks do this.

http://www.boggstool.com/

Our liquid honing process can resharpen tools once considered too difficult to salvage. With our abrasive blast we relief grind taking material from the back edge of the tool to reform and sharpen the edge. Our process will give you the sharpest edge possible.

[george wilson]

I have told this story before: In about 1958 muriatic acid could be bought in sealed plastic cubes about 4" cubic. To open them,you had to snip off the corner of a flap. I had a cube of this way over on the opposite side of the garage from where the tools were kept. I noticed that the CHROME plated wrenches were getting a little rust on them. I cleaned them off. Some days later,the rust was back. I got to looking around,and saw the acid,still sealed and never used. I took it away and poured it out. The rusting ceased.

Keep your acid well away from the shop as advised.

I have sharpened needle files by reverse plating (stripping) them in an acid solution. The blacksmith shop in Wmsbg. got one of those kits that uses a PVC pipe with acid.

I haven't experience with the sand blasting method,but have heard of it. I tend to think it might work best with very coarse tooth files. I think the sand grains might be larger than the gaps between the teeth of finer toothed files.

[Gary Daniel]

I took a class a few years ago at Mark Adams school. http://www.boggstool.com/liquidhone.htm was a company that was highly recommended for reconditioning files. Their website explains the process they use. I have no personal experience using them.

[David Keller NC]

I soaked about a dozen of my files in muratic acid, forgot them for about three hours. They came out great!, definaltly sharper than they were. Thanks for the info.

Leigh - From a chemistry standpoint, muriatic acid is not ideal for steel tools. The reason is that muriatic acid is hydrochloric acid, and the chloride ions actually cause corrosion in steel in a different way than other acid anions (like the sulfate ion in sulfuric acid or the phosphate ion in phosphoric acid). In particular, the chloride ions will "get into" the steel and cause pitting.

That doesn't mean that muriatic acid doesn't work, it certainly will as will all other strong acids. But it's critically important to actually neutralize the HCl, not just wash it off (as Chris suggests when noting that it should be neutralized by a soda (sodium carbonate, or washing soda)).

Also, hydrochloric acid is dangerous, and not just from burns from the liquid. Specifically, strong muriatic acid emits hydrogen chloride, which when inhaled will form hydrochloric acid in the linings of your sinuses and lungs. Similarly, most other strong, concentrated acids can do real damage if you get a snootful of the fumes.

That might be why "pickle juice" is often recommended. The concentration of acetic acid in vinegar is low; so low that it won't burn your skin nor create enough fumes to do damage to the linings of your sinuses, lungs and esophagus. Citric acid also works, and is just as safe as vinegar, with the advantage that you can adjust the concentration since it comes as a powder, and it has no annoying smell unlike vinegar.

[David Weaver]

There's always the lant (uric acid) option, too, for the mutton tallow and tar bucket users (i.e., the folks who don't like to use new tech or commercial products in general).

Just don't tell the wife or shop visitors what it is.

Can't beat the price on it, either.

[Leigh Betsch]

I'm pretty careful around acid. I did this outdoors, and stayed up wind (under my satellite dish, hope it doesn't rust out!). Immediately after I pulled the files out of the acid I plunged them into a mix of baking soda (didn't have any washing soda) and water. I hope this neutralized the acid. It seamed to work very well, no surface rust formed at all.

I visited a metal plating shop back in the 80's, lots of open vats of plating chemicals with parts hanging in them getting treated. The walls and steel beams of the place were all rusted and corroded. I can't imagine how bad that was to the people that worked there. Hope it's better these days.

[Leigh Betsch]

There's always the lant (uric acid) option, too, for the mutton tallow and tar bucket users

If I could get the horse to drink Budweiser I could get this option to work quite well!

[Gary Curtis]

Boggs Tool gave a presentation at my WoodWorking club in Los Angeles. Afterward, I decided to take a drive over to see their operation. I took about 20 files with me. Many from the 40's and 50's. Boggs sharpens files by steam blasting the teeth with an abrasive.

They returned my files by UPS, nicely wrapped individually in brown butcher paper. How's this for sharpness? I ran my finger along the teeth of a course rasp. I got multiple cuts, complete with blood on my fingers. An acid bath isn't going to give you those results. And since you only need to sharpen files once every 20 years, send them to Boggs. Let the pros do it. The cost is minimal.

[Jessica Pierce-LaRose]

I wish my files went 20 years between sharpenings. Maybe I need to take better care of them. Or is that 20 years on wood, and not metal?

[george wilson]

Reminds me of Garrett Hack telling me he'd had the same blades on his thickness planer for 20 years!:)

According to the old time books I like to read,a file used on steel is good for about 40 hours work.

[Gary Curtis]

The files I sent to Boggs were given to me by my machinist father. He worked at A.O. Smith and then at Hughes Aircraft. I don't know where I got that 20-figure from. Either Dad or from speaking with Boggs.

Obviously wood would damage file teeth a lot less than metal. Same for soft metals versus steel. While I was building a new home and shop, and in the mode of acquiring tools and WWing books I read Leonard Lee's Complete Sharpening. He includes quite a few electron microscope photos of various cutting edges.

Deterioration of a sharp edge begins a few hours after grinding. Working with metal that doesn't present a problem. Just spray with Boeshield or WD-40. But there's another route you can take. Go to a bicycle shop and get one of the liquid wax chain/cable lubricants such as White Lightning. I saturated a rag and lightly wiped the files, plane blades and chisels. It dries hard and flakes off. So a quick rub with steel wool and wood can be finished after working with a protected tool.

[Chris Fournier]

If I could get 20 years out of a file I wouldn't consider sharpening the things! I have pattern makers rasps that I treat like fine china, they only see wood and you can see the cutting edge going dull quite easily and quite quickly. $65.00 a crack! I acid sharpen these every couple of years.

[george wilson]

Some woods can be just about as hard on files as metal. They may contain silica deposits sucked up in the wood as it grew.

Speaking of rasps,I have had #59 Nicholson rasps so aggressive,I was glad when they dulled down a bit. They grabbed so badly that they were hard to use. Guess that may be a past concern now that they are made in Mexico. I hear the teeth don't look the same as the old ones at all. Any experience with that,anyone?

[Chris Fournier]

http://www.boggstool.com/

Our liquid honing process can resharpen tools once considered too difficult to salvage. With our abrasive blast we relief grind taking material from the back edge of the tool to reform and sharpen the edge. Our process will give you the sharpest edge possible.

Thanks for the link Johnny! I noticed a typing error on my part; I meant to say "...that some folks don't do this."

[Rick Whitehead]

Some woods can be just about as hard on files as metal. They may contain silica deposits sucked up in the wood as it grew.

Speaking of rasps,I have had #59 Nicholson rasps so aggressive,I was glad when they dulled down a bit. They grabbed so badly that they were hard to use. Guess that may be a past concern now that they are made in Mexico. I hear the teeth don't look the same as the old ones at all. Any experience with that,anyone?

Yes, I recently bought a Nicholson #50 from Jamestown. It is made in Brazil, and definitely isn't as sharp as the American-made Nicholson #49 I bought a few years ago.
I'm debating whether to send it to Boggs, or try to sharpen it myself with citric acid.I've used citric acid before, with good results on some dull files.
Rick

[ray hampton]

If I could get 20 years out of a file I wouldn't consider sharpening the things! I have pattern makers rasps that I treat like fine china, they only see wood and you can see the cutting edge going dull quite easily and quite quickly. $65.00 a crack! I acid sharpen these every couple of years.

20 Years, maybe but I doubt that the files are use every year, I wore files out after 1 day of use and that are a long time

[David Weaver]

I don't have any nicholson rasps made in mexico, but I've gone through a bunch of made in mexico saw files. They do feel sharp, but they don't last as long as an old file. Nicholson must be making a lot of money off of those four in one chisel/rasp with teeth on the back and front, because they seem to have forgotten that people actually like to use files. I sent their customer service an email and asked if there was somewhere to get made in USA files (assuming maybe they were just making second-rate files for home depot customers) and never got a response from them, so I'm guessing they probably only care about manufacturing as cheaply as possible and finding users who aren't very particular.

I can't remember where the #50 rasp I have was made - maybe brazil or something. The edges on it are pretty ugly. There's so many big wide teeth on it, it's hard to tell if it is up to snuff with sharpness initially for the teeth (I don't think the design lends itself to a user having a feeling of using a sharp tool), but the edges themselves are rough.

[David Weaver]

If I could get the horse to drink Budweiser I could get this option to work quite well!

Either that, or you could put an empty jug on your key chain and carry it around until you filled it!

The wiki entry on lant is pretty interesting. You could find all kinds of things to do with it.

[David Weaver]

Oops, missed Rick's post, but it sounds like he's about as impressed as I am.

I have seen people on another forum suggest that some folks send their *new* files to boggs before they even use them.

[Harlan Barnhart]

Regular old white vinegar is strong enough to eat away tool steel. I gave a beat up diston back saw a vinegar bath to de-rust it and forgot about it for a day or two. The vinegar solution was maybe one to four with water. It ate the teeth nearly off. I don't know if it did other damage since I haven't found the time to refile the teeth. The rust was gone though...

[Bob Glenn]

I have read about, but not tried this method. I understand years ago they used to soak them in urine. I think I'll just buy new ones!

[David Weaver]

Yeah, that's the lant. Except lant is aged, I guess it loses some of its offensiveness with age. Among the things wiki says it was used for:

* glazing pastries (!)
* flavoring ale (you could request single lant or double lanted ale) (!!)
* cleaning floors
* freshening breath (!!!)
* and various industrial uses like processing wool, ...

No toolmaker editors at wiki it appears. I first heard of it from Jack over on WN when either I or someone else complained about how easily old files rust, and how quickly they dull with planemaking.

[george wilson]

I think I'll stick to mouthwash. Urine was used for a myriad of things in past centuries,though. There were collectors who went to houses and collected it every day. It was much used for cleaning wool,dying, I think also for making salt peter for gunpowder. Many other uses.

[Harlan Barnhart]

Yeah, that's the lant. Except lant is aged, I guess it loses some of its offensiveness with age. Among the things wiki says it was used for:

* glazing pastries (!)
* flavoring ale (you could request single lant or double lanted ale) (!!)
* cleaning floors
* freshening breath (!!!)
* and various industrial uses like processing wool, ...

No toolmaker editors at wiki it appears. I first heard of it from Jack over on WN when either I or someone else complained about how easily old files rust, and how quickly they dull with planemaking.

Ya know, Wikipedia isn't always right. In I would HOPE this example represents someone's idea of a joke. Probably not.

[george wilson]

Sailing ships out for long voyages,like whalers carried a barrel at the bow. Urine was collected there and used for washing clothes as they couldn't spare fresh water,and salt water washed clothes would chafe the skin badly.

I think I'd have been the dirtiest sailor aboard!!

[Curt Putnam]

There's always the lant (uric acid) option, too, for the mutton tallow and tar bucket users (i.e., the folks who don't like to use new tech or commercial products in general).

Just don't tell the wife or shop visitors what it is.

Can't beat the price on it, either.

I thought that was reserved for hot mortars when no water is about......<g>

[george wilson]

After putting up copper drains and downspouts on houses,the workers used to urinate on them to start the aging process off (many years ago).